Michael Fassbender and Mia Wasikowska in the film adaptation of Jane Eyre (2011). Photograph: Focus/Everett/Rex Features

Some life stories are so canonical that they don’t bear retelling, so much as demand it. That’s why every 20 years or so, we want – and get – a new biography of Charlotte Brontë, that patron saint of every bookish brown mouse who has ever screamed silently to the world “one day you will notice me and be dazzled by my sun”. The tale of how a poor, plain, provincial girl turned a lifetime of material and emotional lack into the thrilling art of Jane Eyre and Villette is so consoling that it is impossible not to ask for it again and again.

Each retelling, of course, gives us a slightly different Charlotte Brontë, one who Janus-like faces back to her own time while also speaking to the biographer’s own. Elizabeth Gaskell writing in 1857, two years after Brontë’s death, was determined to rescue her friend from any suggestion of constitutional “coarseness” – many critics had condemned Jane Eyre as an unladylike book, even a wicked one. Painting in loose, novelistic strokes, Gaskell explained to her readers that if they had been locked away in a remote parsonage with two dead siblings buried virtually in the garden and a father who came down to breakfast with a loaded pistol, then they too might grow up with an imagination warped towards the morbid. That didn’t mean, Gaskell insisted, that Miss Brontë wasn’t unimpeachably wholesome in her everyday, bread-and-butter, life.

In the pragmatic 1990s, Juliet Barker worked hard to clear away the consequences of Gaskell’s well-meaning gothicisation by rebuilding the Brontës’ story on solid historical grounds. In particular Barker challenged her portrayal of Patrick Brontë as a storybook ogre. Charlotte too was transformed from a sequestered tragic heroine into a chippy spinster who carefully stage-managed her rise to literary fame by persistently pushing herself and her work, even the duff stuff, before the public.

Writing to celebrate the forthcoming 200th anniversary of Brontë’s birth, Claire Harman pursues a golden mean. Her protagonist is both fervent dreamer and cool realist, imaginative artist and clear-eyed professional. In a bravura opening scene Harman sets out her stall. It is 1 September 1843 and 27-year-old Brontë is close to breakdown, having been left alone during the dragging summer holidays at the Brussels boarding school where she has been working as a student teacher for the past two years. Racked with miserable longing for Constantin Héger, the charismatic married colleague with whom she is desperately in love, Brontë sets out on a feverish walk. Without knowing exactly how, she finds herself entering the city’s cathedral. And there, amid the looming angels and incense fug, Miss Brontë of Haworth Parsonage, raised to repudiate Romanism in all its slavish forms, slides into the confession box and mumbles her sins – her choking desire for a married man, perhaps – to the priest.

We know all this because Brontë, tickled at her own transgressive daring, wrote a letter the next day describing the sequence of events to her sister Emily. But we know it, too, because she gives near enough the same experience to Lucy Snowe, the heroine of her final and perhaps finest novel, Villette. In one of the most memorable scenes in Victorian literature, Lucy, high on her love for Paul Emanuel (not actually married, but so elusive that he might as well be), floats in anguish through the dull city streets before stumbling into “an old solemn church” where she finds herself making a confession to a kind but puzzled priest. Gaskell, usually unshockable, was so stunned by the delirious sensuality of the scene that she asked Brontë whether she’d been on drugs when she wrote it.

Biographically, the cathedral scene is crucial for Harman because it allows her to make a link between Brontë’s spiritual confession and her growing desire to speak her truth to the world at large. Within a year of coming away from the grille rinsed in “solace”, she would be writing her first novel while simultaneously sending out her poetry to publishers. But the scene as rendered in Villette gains extra importance for Harman because it shows Brontë making a new kind of fictional narrative, one that is more concerned with the flutters and surges of the narrator’s inner consciousness than the external demands of the plot.

As a highly experienced biographer, Harman has too much integrity to suggest that this idea of her subject as a proto-modernist is entirely fresh. Nor does she even hint that she has uncovered any new documentary sources about her. Instead, she wisely concentrates on rounding out and deepening aspects of the author’s life that have been previously scanted or skewed. Particularly fine is Harman’s reading of how the tortuous, sexless love affair between Héger and Brontë could ever have been allowed to reach such heights – or depths. Previous biographers have tended either to castigate Héger as a married flirt who led Brontë on, or they have painted her as a disordered spinster, randy with celibacy, quite capable of spitefully destroying a man who refused to make love to her.

Harman, by contrast, suggests that what we may be looking at is primarily a cultural misunderstanding. Héger routinely lavished his pupils with a repertoire of kisses, pats and affectionate glances. Brontë, raised with brisk Yorkshire non-showiness, may simply have misread pseudo-parental tenderness as a special favour. What’s more Mme Héger, far from being as sly and vengeful as her fictional avatar Mme Beck, was simply a sensible businesswoman who realised the damage to her school’s reputation if gossip emerged about a tendresse between her husband and the plain, nervy English governess. Deciding not to respond to the stream of yearning, abasing letters that Brontë wrote once she had returned to Haworth wasn’t a vicious move on the Hegers’ part, but simply self-preservation.

Harman’s sane, unshowy retelling is exactly right for the bicentenary next April. It never insults the reader’s intelligence by pretending that it has new, startling truths to impart. Instead it gathers up the best of what has been written before and deals tactfully and decisively with the sillier aspects of Brontë mythology. The result is a retooled classic biographical narrative, shipshape and serviceable for the next 200 years.